Transmit-receive device



Sept. 8, 1959 H. c. ALEXANDER f 2,903,655

TRANSMIT-RECEIVE DEVICE Filed March l, 1957 :24 new l l@ d 4A` Y 777'F`\G.4 Tlc. 2. anni, ,yan

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HERBERT C. ALEXANDER United States Patent O TRANsMrr-RECEIVE DEVICEHerbert C. Alexander, Peabody, Mass., assigner to Bolnac LaboratoriesInc., Beverly, Mass., a corporation of Massachusetts Application March1, 1957, Serial No. 643,390

4 Claims. (Cl. 3133-113) The present invention relates to gaseousdischarge switching devices and more particularly to transmitreceivedevices employed in microwave frequency radar systems.

The transmit-receive tube or TR as it is commonly referred to in the artcomprises a metallic waveguide envelope containing an ionizableatmosphere and a plurality of resonant elements to facilitate both ahigh power gaseous discharge and low power transmission of microwavesignals to the receiver apparatus. Amongst such resonant elementscommonly employed are the input 'window with a dielectric coveredaperture, paired metallic inductive iris members and capacitivedischarge gap electrodes. Recent developments in the art have resultedin multiple-aperture input windows to minimize the heat transfer problemincident on such elements when the intense gaseous discharge occurs.Such structure will `also lower the Q factor of the window to therebyincrease the operating bandwidth of the device.

The present invention has for its primary object the provision of anovel capacitive and inductive resonant structure to be incorporatedwith multiple-aperture input Iwindow structures yto result in a TRdevice having an overall lower Q factor than prior :art devices.

Another object of the invention is to provide a novel multiple-irisresonant member with discharge gap electrode members for each irisopening in a unitary structure.

Briefly the objects enumerated are achieved by improved flat metallicplate members disposed within a hollow waveguide envelope having themultiple-aperture resonant window members hermetically sealed at theends thereof. Each plate member comprises a plurality of transverse iris`openings to match the resonant window structure. Conical-tipped membersare introduced through opposite sides of the plate member and extendinto the openings. A double ended conical-tipped member is supported bythe metallic section between the openings with a portion of each tipextending into the opening to thus define with the first members aplurality of resonant discharge gaps in parallel. The resultantstructure provides adequate voltage step-up for the radio frequencydischarge and is a very low Q structure compared to prototype singleiris structure.

Other objects, features and advantages will be evident afterconsideration of the following detailed speciiication together with theappended drawings in which:

Fig. 1 is a detailed cross-sectional view of the illustrativeembodiment;

Fig. 2 is a view partly in section along the line 2-2 in Fig. 1;

Fig. 3 is a perspective view of another embodiment; and

Fig. 4 is a detailed cross-section view `along the line 4-4 in Fig. 3.

Referring now to Figs. 1 and 2 the embodiment shown comprises a sectionof rectangular hollow pipe waveguide 1 having hermetically sealed `atlthe ends thereof a resonant window element 2 and 3 having a pluralityof transverse apertures enclosed by dielectric members 4 and 5 andseparated by a metallic portion 6 of the overall window frame. Theseresonant window elements may be fabricated in accordance with theteachings of U.S. Patent 2,748,351, issued May 29, 1956, and are notclaimed as a part of the present disclosure. Flanges 7 and 8 secured towaveguide 1 provide means for securing the device to -other waveguidestructure.

In accordance with the teachings of the present invention, I provide aplurality of flat metallic plate members 9 and 10 within the waveguide 1spaced apart the conventional quarter-wavelength distance. Plates 9 and10 are provided with a plurality of transverse resonant iris openings11, 12, and 13, 14 in alignment with the resonant window apertures. Withthis structure, there is presented in the path of electromagnetic wavespropagated through the system two half-height waveguide structures whichprovide ya substantially lower Q than conventional single irisstructure.

Within each plate iris opening I provide the capacitive component of theresonant discharge gap circuit by means of pointed members supportedwithin the plate member. In Fig. 2 wherein plate member 9 is illustratedthere is shown a threaded conical-tipped member 15 and 16 introducedthrough each broad wall of the plate. A double-conical tipped member 17is supported by the metallic wall portion 18 between the openings withthe conical ends 19 and 29 cooperating with threaded members `15 yand 16to define two resonant gaps 21 yand 22. Adjustment of members 15 and 16permits tuning of the gaps to the desired resonant frequency. Theresultant discharge gaps will be in parallel each within half-heightwaveguide. This eectively lowers the Q of the resonant circuit whilestill maintaining an adequate voltage stepup gradient in each gap.

Plate member 10 provides a similar structure, however, the upperthreaded member 23 may be hollow to provide for an ignitor electrode 24to be introduced therein. The tip 25 will be open and permit theintroduction of electrons into the discharge gap 41 to `facilitatepartial ionization of the gaseous atmosphere. A glass bulb 26 ysupportsthe electrode 24 and is in turn sealed to a collar 27 secured to thewaveguide 1.

An ignitor electrode 39 supported by bulb 40 is provided within lowerthreaded member 38 to ionize the gas in the vicinity of discharge gap42.

While l have shown a plurality of plate members hav- -ing the dischargegap members positioned therein it will be evident that with changes inthe frequency bandwidth, the plate members may be thinner to provide theresonant condition. In such embodiments the teachings of the inventionmay still be practiced by providing split-conical 'tipped members whichwhen assembled will extend beyond the plane `of said plate-members.

Another application of the present invention resides in a novelmultiple-aperture resonant window structure having the plural dischargegap structure incorporated therein. Referring to Figs. 3 and 4 plate 30of a dielectric or ceramic material is provided with resonant openings32 and 33 and coated with a metallic paint or covering 31 on both sides.The art of metallizing or painting such materials may be ascertainedfrom U.S. Patent 2,683,863, issued to T. P. Curtis, on July 13, 1954,and U.S. Patent 2,770,784, issued to R. H. Hatch, on November 13, 1956.

Conical-tipped threaded members 34 and 35 are then positioned as shownto extend partly into each resonant opening 32 and 33. The double-tippedmember 36 may then be positioned within portion 37 with each end deningwith the aforementioned threaded members the plural discharge gaps. Theopenings 32 and 33 may then'be enclosed'by windows 43 and 44 to definehollow chambers which may be filled with an ionizable atmosphere. Thecomplete window assembly may be sealed to the ends of the waveguideenvelope by conventional Vdielectrictometal sealing techniques.

A Vcomplete TR tube structure incorporating resonant elements of thepresent invention may be exhausted and lled with an ionizable atmosphereunder reduced pressure in the manner well known in the art.

With the multiple discharge gap low Q resonant elements described,improved electrical characteristics, ineluding increased bandwidth andlower spike and iiat leakage power values, may be realized. It will beevident that vthe invention will be equally applicable to other multipleiris opening structures and any number of the spaced plate memberelements may be employed in waveguide rtransmission systems.

VWhat is claimed is:

Jl. In lcombination with hollow pipe rectangular waveguide structure, aresonant element adapted to be mounted within said waveguide structurecomprising a metallic plate member having broad and narrow walls and apluality of ltransverse resonant iris openings deining therebetween asolid metallic wall, a resonant discharge gap /delined within eachresonant iris opening by means of 'single conical-tipped membersextending inwardly from the broad walls of said plate member with theends thereof positioned within said iris openings and a double-conicaltipped member supported by said metallic wall with the ends thereof inaxial alignment with and spaced from said single conical-tipped members.

2. In combination with hollow pipe rectangular waveguide structure, aresonant element adapted to be mounted within said waveguide structurecomprising a metallic plate member having broad and narrow walls and aplurality of transverse resonant iris openings defining therebetween asolid metallic wall, a resonant discharge gap defined within eachresonant iris opening by means of threaded conical-tipped memberspositioned within the broad walls of said plate member with the endsthereof extending into each iris opening, a double conical-tipped membersupported within said metallic wall with each end in axial alignmentwith and spaced from said threaded conical-tipped members, said gapspacings being adjustable by axial movement of said threaded members.

3. In combination with ia section of hollow pipe rectangular waveguidehaving "multiple-apertured resonant windows sealed `at the ends thereofto define a hermetically sealed envelope, a resonant element spacedwithin said waveguide section a distance of one quarter of a wavelengthaway from the ends thereof, said resonant element comprising a metallicplate member having broad and narrow walls and a plurality of'transverse resonant iris openings defining therebetween a solidmetallic wall, said iris openings being inalignment with said windowapertures, a resonant discharge gap defined within each iris opening bymeans of afconical-tipped screw member extending into each broad walloff said plate member with the ends thereof positioned within each irisopening, a double conical-tipped member positioned within said metallicwall with each end in axial alignment with and spaced from said screwmembers and a iilling of a gaseous atmosphere within said envelope.

4. A resonant window element for gaseous discharge waveguidetransmission control devices adapted to be sealed at an end of a sectionof hollow pipe rectangular waveguide comprising a plate member of adielectric material lhaving a plurality of'resonant openings therein, ametallic-coating on both faces of said plate member defining a pluralityof resonant apertures, a resonant discharge gap dei-ined within eachresonant opening Vby means of a single conical-tipped member extendinginwardly `from the top and bottom walls of said plate member with theends thereof'positioned within said resonant openings, a double-conicaltipped member positioned within said plate member inthe area between`said resonant openings with the ends thereof in axial alignment withand spaced `from said 4single conical-tipped members, window enclosuressealed at opposite ends of said openings to detine hollow chambers andan ionizable atmosphere within said chambers.

References Cited in the iile of this patent UNITED STATES PATENTS2,524,268 McCarthy Oct. 3, 1950 2,730,645 Kenty Jan. 10, 1956 2,748,351Varnerin lMay 29, 1956

